Ozone is increasingly becoming recognized as a detrimental agent for skin cells. Ozone can affect lipids, proteins, nucleic acids and sugars but is especially severe to key antioxidants located in skin cells. The damage appears to be most severe at the surface layers of skin, and diminishes as one probes into deeper dermal and epidermal layers. Ozone, which is generated by a number of natural sources such as lightning, is also generated by various industrial sources, such as the burning of fossil fuels, and in particular, the emission from automobiles, which are a leading cause of urban smog. Ozone is formed when reactive oxygen radicals combine with oxygen gas to form a molecule that contains three moles of oxygen as can be seen in the empirical equation:O2+O→O3 
In particular, it is now generally recognized that ozone will diminish the amounts of vitamins C and E in the upper layers of the stratum corneum as well as oxidize key lipids in the bi-layer of the stratum corneum. In addition, ozone has been implicated in protein and nucleic acid damage as well. Thiele, J. et al., “In-Vivo Exposure to Ozone Depletes Vitamins C and E and Induces Lipid Peroxidation in Epidermal Layers of Murine Skin” Free Rad. Biol. Med. 23, 385-391 (1997). Vitamins C and E are key natural antioxidants that offer important defense mechanisms against the ravages of ozone to the deeper layers of the skin. The lipid bi-layer is the most important physical barrier between the interior of the human body and external elements. Deterioration of the lipid bi-layer increases trans-epidermal water loss and leads to drying and cracking of the skin. Methods to measure the effects of ozone stress on human skin and human skin-mimics are disclosed in Cotovio, J. et al., “Generation of oxidative stress in human cutaneous models following in-vitro ozone exposure,” 15, 357-362 (2001) and Weber, S U. et al., “High-Performance Liquid Chromatography Analysis of Ozone-Induced Depletion of Hydrophilic and Lipophilic Antioxidants in Murine Skin,” Method Enzy., 319, 536-546 (2000). In addition, melanin is a key photo-protective pigment located in the skin and hair that has not previously been shown to be a target for ozone degradation. Other key cutaneous lipids that ozone can attack include cholesterol, cholesterol esters, free fatty acids and ceramides that make up the lipid bilayers of the skin.
Damage to nucleic acids can lead to cellular mutations and apoptosis of important skin cells. Such skin cells include, but are not limited to fibroblasts, keratinocytes, dermal papilla, melanocytes, macrophages, corneocytes, Langerhan cells, neutrophils, adipocytes, sebocytes, and nerve cells which reside at the surface of the skin. Likewise, ozone can deteriorate proteins and sugars that comprise the extracellular matrix and natural moisturizers in the skin.
The use of cosmetic products to protect the human body, and in particular the skin, from the damaging effects of ozone is known. For example, Japanese patent JP60215609, published October 1985, discloses the use of melanoidins to protect the skin against ozone. European patent EP1108419, published June 2000, discloses the use of combinations of hesperetin and curcumin derivatives in topical applications to protect the skin. International Patent Application WO0059462, published October 2000, discloses the use of combinations of oxidoreductases and proteinase inhibitors to protect the skin against the damage caused by increased ozone concentrations in the atmosphere. Likewise, International Patent Application WO0202075, published January 2002, discloses the use of creatine and creatine derivatives as a prophylaxis for the symptoms of ozone induced skin lesions and inflammatory or degenerative skin conditions.
In a similar fashion to human skin cells, yeast respond to the presence of ozone. High concentration of ozone is typically lethal to yeast. However, it has been suggested that lower concentrations of ozone may not only be nonlethal, but may also influence the yeast to increase production of certain proteins, including glyceraldehyde-3-phosphate dehydrogenase (GAPDH). GAPDH is a key “housekeeper” enzyme that is responsible for oxidatively converting glyceraldehyde-3-phosphate into 1,3-diphosphoglycerate in human skin as part of the glucose cellular enzymatic pathways. It is known that the enzymatic activity of GAPDH is affected by oxidative stress and ultraviolet light. Hinze, H et. al., “Effect of ozone on ATP, cytosolic enzymes and permeability of Saccharomyces cerevisiae,” Arch Microbiol. 147, 105-108 1987.
The use of yeast and derivatives thereof has become quite popular in topical cosmetic and therapeutic applications. For example, active yeast lysates have been sold in the personal care industry for many years. Historically, these products have been marketed and sold as activators of tissue oxygen uptake. It has been found that stressed yeast lysates will stimulate growing cells to increase their oxygen consumption. Additionally, it has been discovered that yeast tissue respiratory factors could also stimulate collagen production in skin.
For example, U.S. Pat. No. 2,239,345, issued April, 1941, discloses a method for improving the uptake of oxygen in living yeast cells by application of components derived from yeast. U.S. Pat. No. 5,057,320, issued October, 1991, discloses yeast compositions containing picolinic acid to increase oxygen uptake in living mammalian skin cells. Additionally, U.S. Pat. No. 5,514,591, issued May, 1996, discloses improved methods to measure the ability of yeast extracts to stimulate oxygen uptake in human skin cells. Despite previous attempts to increase oxygen uptake in human skin cells, there is no solution that directly addresses the need of ozone protection for the skin.
Therefore, what is needed in the art is a product that provides ozone protection to skin cells and skin cell components which include, but are not limited to nucleic acids, the extracellular matrix proteins, vitamin reservoirs, and the like.
It has been surprisingly found that Saccharomyces cerevisiae, more commonly known as Baker's Yeast, respond well to growth stresses, such as heat shock, ozone, peroxides and ultraviolet light. Surprisingly, the stress provides enhanced production of stress response agents, or protective cell components in the yeast. These stress response agents have therapeutic effects on human skin cells.